From his law practice in the heart of Germany, Stefan Grigat says the federal government is responsible for triggering a crime wave.

The Detmold town councillor blames Angela Merkel's migration policy for upending the country. By allowing in about a million asylum seekers as others in Europe shut their borders, the government trampled on the constitution and turned Germany into "the world's social-welfare office." In the process, he says the chancellor has destroyed the Christian Democratic Union party to which they both belong.

"Merkel has succeeded in turning everybody in Europe against us," said Grigat, 52. "If we don't manage to draw a clear line here, both Germany and Europe will soon cease to exist."

In Detmold as across Germany, communities are riven over a government-sanctioned influx of refugees that has forced urban and rural regions alike to confront the uncomfortable realities of globalization. It's prompted a volatile mood in the country as Merkel prepares to seek a fourth term in German elections next fall, making her vulnerable like rarely before.

While economic malaise in Germany is limited given record low joblessness and growing disposable incomes, Merkel's opponents cite her open-doors mantra as evidence that she doesn't care about voter concerns. At one stroke, the chancellor whose natural caution was denounced as indecision throughout crises such as in Greece finds herself assailed for making an intuitive call that alienated much of her party as well as the public.

"Merkel has been seen over the years as a cold tactician of power, but in the refugee crisis she turned an emergency into an opportunity to take a stand, and took a decision of historic proportions," Ulrich Sarcinelli, a politics professor at the University of Koblenz-Landau, said in an interview. "Ultimately it'll be a major chapter in her legacy."

Tension over migration is just below the surface in Essen as CDU members opened their annual convention on Tuesday. Before running in 2017, Merkel faces re-election as party chairwoman in a members' ballot that will be scrutinized for clues to her political fortunes.

Even amid the criticism, "many of our members and many German citizens are happy that Angela Merkel wants to serve for another four years in difficult times," Peter Tauber, the CDU's general secretary, said in a Bloomberg Television interview. About two-thirds of Germans, or 64 percent, said it's a good thing that Merkel is running again, according to an FG Wahlen poll in November.

Detmold, situated just off the main Autobahn route between Essen and Berlin, is a showcase for the split at large. The town of about 75,000 is best known for its 174-foot-high statue of Hermann, a first-century warrior who united the Germanic tribes to annihilate a Roman army in the nearby Teutoburg Forest in the year A.D. 9. The battle permanently pinned back Rome's imperial ambitions and established the Teutons as an independent people.

Two millennia later, the war zones are in Syria, Iraq and Afghanistan, and Detmold is host to about 650 of the refugees who fled to the safety of Germany during the migrant crisis that peaked a year ago. They're being welcomed, but the decisions in Berlin that allowed them into Germany are dividing the regional CDU chapter.

Wilfried Mellies' home is a shrine to Hermann. The CDU mayor of the Detmold district of Hiddesen lives a five-minute drive from the monument, and hundreds of figures of the Cheruskan chieftain adorn his house, from miniature plastic toys to life-sized wooden likenesses. He's also a fan of Merkel's migration policy.

Just as the monument became a tourist magnet, attracting visitors and money, migration is "a huge chance for Germany with so many people coming here," said Mellies, 70.

"This is why we also have this open culture when it comes to refugees," he said. "Change has always happened."

In Detmold, the CDU has backed town council decisions on refugees, arguing they can't simply be denied a place to stay. "Of course we also have people here who are afraid or who even openly reject foreigners," Mayor Rainer Heller, a Social Democrat, said in the town hall. "But we also have a Prussian administration which gets things done."

Detmolders adjusted over time. A building complex close to the town center once used by British troops now houses around 500 refugees. Groups of men hang out on the grass, while children play on a newly built playground.

Yet government assertions that refugees would help to fill the labor gap have turned out to be an illusion. David Nitschke, CEO of Jowat, a Detmold-based producer of industrial adhesives, says he's offered traineeships to refugees but they prefer earning money to gaining new skills.

"The idea that these people could solve our problem of skilled labor shortage is pure wishful thinking," Nitschke said.

As Merkel returns to Essen, where she was first elected CDU leader in 2000, she'll be on the defensive. Though polls suggest her bloc will remain the biggest party in the federal parliament next year, Christian Haase, who represents Detmold in the Bundestag, says some of his fellow CDU lawmakers "are pretty scared" for their seats.

The party will still rally round and back their chancellor, according to Sarcinelli. "The CDU snaps to attention when power is at stake -- even when it has considerable internal disputes such as now," he said.